The present invention relates to a process for the production of oxygenated fuel compositions. Specifically, the invention relates to a process for the production of an oxygenated fuel composition comprising gasoline and isopropanol. The present process also provides for the production of an olefinic gasoline blending stock by the oligomerization of excess olefins. It is, therefore, possible in accordance with the present invention to obtain a high octane fuel composition without the necessity for alkylation.
The process of the present invention is also more economical than prior processes, since it employs a dilute feed. In accordance with the present invention, it is possible to achieve reasonably high conversions without resorting to a costly pre-reactor C.sub.3 .dbd./C.sub.3 splitter to concentrate propylene in the feed.
As is well known, alkylation can produce a premium grade gasoline component from olefins by reaction with isoparaffins such as isobutene or isopentane. Such alkylation can be conducted thermally at high temperatures and very high pressures, but is preferably done at low temperatures in the presence of catalysts. Such catalytic alkylation proceeds quite readily and, as long as a sufficient excess of the C.sub.4 or C.sub.5 isoparaffin is present, results in substantially complete conversion of the olefinic feed constituents into valuable C.sub.7 to C.sub.9 branched chain paraffins of high antiknock value and relatively low volatility.
Refineries have, however, experienced a shortage of isoparaffins, particularly isobutane and, therefore, have an excess of olefins. So a way to place these olefins into the motor gasoline pool is needed.
At the same time, gasoline octane requirements have increased and use of the traditional lead-containing gasoline additives has been largely discontinued. It has, therefore, become necessary to find alternative means to produce high octane fuel compositions without the necessity for alkylation.